“On-set” or “on-site” video and film production often requires the use of incident and reflected (spot) light-meters to adjust scene lighting and camera gain or aperture. Many times the light-meter measurement and lighting adjustments are done in relative values such as F-stops. F-stops are well known and derive from film exposure and camera aperture or speed adjustment, which is typically adjusted in F-stop increments. The so called F-stop derives from the Focal Ratio or F-number, a dimensionless ratio of focal-length divided by the effective aperture of the camera lens. For example, one f-stop, or “stop”, corresponds to an area increase of 2× or 3 dB in light power but the F-number changes by only sqrt(2). It is typically the F-number that is marked on the lens iris or aperture adjustment.
Presently, both film production and video production use electronic imagers within the cameras typically providing a very large dynamic range and adjustable gain (6 dB/stop). For example, according to Wikipedia, film negatives have about 13 stops compared to 14.4 stops for a typical (e.g., Nikon D800) DSLR camera. In video and movie film production, the traditional Gamma (power-law) correction as well as newer log processing within the camera can maintain a large portion of that dynamic range when compressed into a 12-bit or even 10-bit resolution digital video output. It is very important to determine how well that dynamic range is being utilized based on camera adjustment (gain/aperture) and scene lighting. Typically this is done on the camera output signal by viewing the output on a picture monitor (<10 stops of dynamic range). Also note that by simply looking at a well calibrated picture monitor, the dynamic range is limited by the adapted eye to about 7 stops, which leaves invisible detail in the dark portions of the output. A video Waveform Monitor is often also used, but currently these Waveform Monitors are limited to linear voltage indications, with much of the dynamic range near black compressed into just a few mV near 0. Much like the case for analyzing high dynamic range Radio Frequency (RF) signals, a linear waveform scaling is not adequate.
Embodiments of the invention address these and other issues in the prior art.